So far, for example, Patent Document 1 discloses a variable valve operating apparatus for an internal combustion engine, which makes mechanically variable valve-opening characteristics of a valve. This conventional variable valve operating apparatus includes, between a cam and the valve, a rocker arm, which is supported by a rocker arm shaft so as to be rockable and movable in the axial direction of the shaft. Moreover, the above-described variable valve operating apparatus is provided with a helical guide groove in the outer peripheral surface of a camshaft, as well as a gondola including a projection part which is engageable with the guide groove. This gondola is supported by the camshaft so as to be movable in the axial direction and is connected with the rocker arm via a rod.
In the above-described conventional variable valve operating apparatus, an arrangement is made such that with the gondola being moved by a hydraulic actuator, the projection part and the guide groove become engaged with each other, and with the camshaft being rotated under this engagement state, the rocker arm moves in the axial direction of the rocker arm shaft via the gondola. Moreover, it is arranged such that with the rocker arm being moved, cams for pressing the valve are switched.
[Patent Document 1] Japanese Laid-open Utility Model Application Publication No. Sho 62-184118